scribner



(No Model.) 2 ShetsSheet 1. C. E. SGRIBNER.

MULTIPLE SWITCH BOARD TESTING APPARATUS.

No. 427,121. Patented May 6, 1890.

d ozmZ 320M971 (No Model.) 2 Sheets-Sheet 2.

C. E. SGRIBNER. MULTIPLE SWITCH BOARD TESTING APPARATUS.

No. 427,121. Patented Mayb, 1890.

UNITED STATES ATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE \VESTERN ELECTRIC COMPANY, OF SAME PLACE.

MULTlPLE-SWlTCH-BOARD TESTING APPARATUS.

SPECIFICATION forming part Of Letters Patent N0. 427,121,6l2ti38d. May 6, 1890. Application filed December 2'7, 1886. Serial No. 222,706. (No model.)

To cLZZ whom it map concern: a detailed sectional view of one of the loop- Be it known that I, CHARLES E. SORIBNER, plugs. a citizen of the United States, residing at Chi- Like parts are indicated by similar letters cago, in the county of Cook and State of Illi of reference throughout the different figures.

5 nois, have invented a certain new and useful As shown in Fig. 1, branch 01, of the metal- Improvement in Multiple-Switch-Board Testlic circuit is connected through spring-jack ing Apparatus, (Case 128,) of which the folswitches 11 0, one on each of the boards. and lowing is a full, clear, concise, and exact dethence through individual annunciator d, and scription, reference being had to the accomthence through armature e of electro-magnet i0 panying drawings, forming a part of this f, and thence to branch 9 of the metallic cir- 6o specification. cuit, which is permanently connected with My invention relates to multiple-switchthe frames or test-pieces of the switches b 0, board systems of telephone-exchange in which and extends to the subscribers station through telephone-lines, either metallic or ground or the telephone and transmitter to the contactboth metallic and ground, are connected, repoint it near the telephone switch. This spectively, with a switch on each of two or branch 'g, it will be noted, is normally open more switch-boards; and its object is to enaat the subscribers station. A key i is, howble the operator at one board to test any line ever, provided at the subscribers station, so

to determine whether said line is connected that this branch 9 may be closed to ground 20 or busy at any other of the switch-boards, in by the subscriber while he is sending in a order that confusion may be avoided. call.

Heretofore many different test systems The circuit of the ground telephone-line have been employed in connection with mulmay be traced, as shown in Fig. 1, through tiple-switch-board systems for this purpose. the spring-jack switches Z m,'the individual 2 5 As to the state of the art prior to my inannunciator n, and the armature 0 and elecvention herein claimed, reference is made to fro-magnet p of the buzzer to wire g, which is my patents, No. 321,390, of June 30, 1885, and connected with the frames, respectively, of No, 305,021, of September 9, 1884. switches Z and m and through resistance r to My invention herein consists in placing a ground. It will be noted that the ground- 0 buzzer in circuit with the individual annunwire q of the ground-circuit corresponds to ciator in each line in combination with cirthe branch 9 of the metallic circuit, the difcuits and testing apparatus, by means of ferenee being that branch 9 extends to the which, when a test is made, the buzzer will subscribers station,whereit is normally open, cause a tone in the telephone if the line while ground-wire q passes through resist- 5 tested is free. In case the line tested is alame 0" to ground at the central office. This ready in use the circuit through the teleresistance r may be, say, of one hundred and phone test-battery and buzzer will be found fifty ohms, and for the purposes of testing, open, and hence the buzzer will not be set in as will be hereinafter described,is equivalent vibration and no tone will be heard in the to a break in the circuit.

40 telephone. At. the first board I have shown plug 5 with My invention is illustrated in the accompaits point touching the insulated frame of nying drawings, in whichspring-jack b, the other plug of the pair 75 hav- Figure 1 is a diagram illustrative of two ing its metallic heel resting upon the groundtelephone lines connected each with its plate, and the loop-key being in position to 5 switches on two multiple switch-boards and bring the telephone and test-battery into the a buzzer included in the circuit with the ancircuit. WVhen the tip of plug 3 is thus apnunciator of each line and key-board appaplied to the frame of the spring-jack of the ratus at the different boards. Fig. 2 is a dialine to be tested, if said line is free the armagram illustrative of the circuits of a metallic ture e of the buzzer will be set in vibration to 50 circuit at the subscribers station. Fig. 3 is interrupt the circuit and cause a tone in the telephone. This circuit may be traced, as shown, from the ground-plate upon which the heel of plug 25 rests to the tip of said plug f, thence through a strand of the cord to calling-key u, and thence to spring 1), and thence through the telephone and test-battery to point w and spring a; of the loop-key, and thence to calling-key y, and thence to the tip of plug 5, and thence to the frame of spring b, and thence to branch g, and said branch 9 being open at the subscribers station the test-battery will find circuit by branch 2 through the electro-magnet f and armature 6, through annunciator d, through the springjacks c and b to branch at of the metallic circuit, which branch a is connected. through the subscribers bell and generator to ground, as shown in Fig. 2. In my application, No. 222,696, filed of even date herewith, upon which patent No. 383,495 was granted May 29, 1888, I have shown a similar ground branch through the subscribers bell and generator. If there is no break at any of the switches 19 c in the line, armature f will vibrate in the circuit including the telephone and test-battery, and the operator, listening at the telephone, will know by the sound caused by the buzzer that the line is not connected at any one of its switches. If, however, a plug were inserted in switch 0 or any other switch in the line, the branch a would be found open at said switch, and the circuit thus being open the buzzer would not respond, and the operator listening at the telephone would hear no tone, and would hence know that the line was in use. By touching the tip of the plug 8 in the same manner to the frame of spring-jack Z line is may be tested. Wire is, extending to its subscribers station, would be there closed to ground in the usual manner and resistance r would be sufficient to cause current to be diverted through the buzzer. Thus if the tip of the plug 5 were applied to the frame of switch Z the circuit would be traced, as before described, from a ground-plate to tip of plug tand thence through the loop-key, the telephone, and test-battery to the tip of plug 8, and thence to the frame of spring-jack Z, and thence by branch 2' through the electro-magnet 19 and armature o of the buzzer, and thence through switches m Z over line 70. In case line were connected through all its switches the was in use.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. A telephone-line, in combination with switches distributed on different boards, a buzzer included in said circuit back of all the switches, said circuit after passing through the buzzer being connected with the insulated frames or.-test-pieces of each of the switches and a telephone and battery included in a normally-open ground-circuit, and switching devices whereby on closing the circuit of said telephone'and battery to the frame of a switch of the line it may be determined whether said line is open at any one of its switches.

2 The combination, with a telephone-line connected with ground at the subscribers station and through switches one on each of two or more switch-boards at the central office, of a branch from the contact-point of the switch on the last board, including a buzzer, said branch, which includes the buzzer, after passing through the buzzer, being permanently connected with the insulated frames of the switches of the line, and testing apparatus, whereby it may be determined at any one of 'the'boards whether the circuit of said line is broken at any switch of the line.

3. In a multiple switch-board system, the combination of spring jack switches, one switch upon each board, circuits connecting with the spring-jacks and to ground, a buzzer included in the said circuit between the last spring-jack and the ground, and testing apparatus whereby an operator may determine at any board whether the buzzer is disconnected at any other board.

In witness whereof I hereunto subscribe my name this 16th day of November, A. D. 1886.

CHARLES E. SCRIBNER.

Witnesses:

GEORGE P. BARTON, 7M. M. GILLER. 

